Hi guys,

Got a call to do a quote today. The guy has a beautiful wooden floor and in the utility room the washing machine sprank a leak. Warped all the floor. The guys chopped out the wood and the floor is concrete.

The distance is about 20mm to get back to the level of the wooden floor in the adjoining rooms so i'm looking to make up around 9-10mm.

He'd brought two lots of tiles some cheap tiles and then the tiles he wanted and wanted to tile the floor twice to get up to the level.

I said this wasn't the best way of doing things and that boarding or self leveling would be the better way of doing it. He didn't seem too hot on the idea of leveling due to expense but I said i'd look into it and get back to him. The floor is 6m2 and concrete

So i have two options:-

Boarding the floor
I know this is not normally common practice for concrete floors but heard that it has and can be done. I understand that 6mm gaps need to be left and screwed at 250mm centres. Is that correct. Would I need to stick the boards down with adhesive aswell to ensure good support? The guy doesn't want ply down incase they spring another leak so was thinking 9mm no more ply or hardibacker?

Self levelling

I've never self levelled before but heard its not too hard. What leveller would be suggested and what sort of cost would i be looking at for that sort of area. How long would it need to be left before tiling onto it.

Thanks in advance Smithy

i'v used the mapei levellers and they are easy enough used,there is a formula on here somewhere to work out the exact amount of leveller needed.If you do go that way make sure to spread it well with flat trowel too and use a spiked roller to let air out.

if you use hardiebacker on a concrete floor, why would you need to screw it? there's not going to be any deflection. It's the route i'd seriously consider

Originally Posted by doug boardley

if you use hardiebacker on a concrete floor, why would you need to screw it? there's not going to be any deflection. It's the route i'd seriously consider

Because 6mm hardie ain't flat Doug and the addy isn't strong enough to hold it down!!! I have been there and ended up drilling and plugging the floor....what a pain in the asp!

would a bit of weight in the middle (whilst addy is setting) not take up the tensile "bow" and pull it flat Russ? I don't know, just hypothesising

why not top it or render over slab cheapest way out or 3 to 4 bags of slc (any one tried laticrete slc suitable for outside work cheap to)

Originally Posted by doug boardley

would a bit of weight in the middle (whilst addy is setting) not take up the tensile "bow" and pull it flat Russ? I don't know, just hypothesising

It isn't just a bow in my experience doug, the edges can curl slightly too. Good stuff as it is, it is not really suitable for bringing levels of a screed/concrete floor up in my opinion. 6mm wedi or similar would be better for this I feel, as that does stay pretty much flat with the adhesive.

So wedi board would do the job then. Does this come in 6mm and 10mm? What would be the fixing process would a flexi adhesive be sufficient without screwing down? Do I still require certain expansion joints

Originally Posted by Smithy153

So wedi board would do the job then. Does this come in 6mm and 10mm? What would be the fixing process would a flexi adhesive be sufficient without screwing down? Do I still require certain expansion joints

That would be the way I would go. Use a 6mm trowel if your floors are flat and I always use flexy addy, anyway so that is what I would use. Expansion jints round the edges and change of substrate if there is one.